I have a BMI of 35 (obese) but have been weight training for 20 years and have a low body fat percentage. It works as a rough guide as it is easer to calculate

I have a BMI of 35 (obese) but have been weight training for 20 years and have a low body fat percentage. It works as a rough guide as it is easer to calculate than body fat percentage. Most people that go to the gym don't have much muscle; so unless someone is a dedicated bodybuilder or powerlifter it's good enough. You can tell just by looking at someone if they have large amounts of body fat!